Improvement of wettability and joint strength using Sn-In-Al-Si-V solder for diamond

摘要

For the precise cutting and polishing of diamond, joining of a diamond to a polishing jig was attempted, and the soldered interface was investigated using an X-ray diffractometer to detect the reaction products and solidification preference in the surface modification of the diamond. If the joining of a diamond to a metal-jig using solder without the graphitization of the diamond is possible, use of a vacuum chamber in the joining process is not necessary. It is also expected that the cracks at the joint interface between the metal-jig and the diamond will not be generated by the thermal stress. Developed solder materials containing a reactive metal of vanadium and an Al-Si alloy are investigated to improve the wettability and the joint strength, since it is difficult to metallize the diamond surface at a low temperature (under 720 K) so as the soldering temperature. In this study, an aluminum element is considered to play an important role in achieving a soldered joint due to a small misfit of 2.30% with vanadium carbide, which is a reactive product between the diamond and the reactive metal of vanadium. In previous cases of the metallization at the temperatures ranging from 720 K to 870 K, the soldered joints of the diamonds were broken by about 1 MPa shear stress. In the case of the metallization at the higher temperature of 920 K, the shear strength reached grater than 30 MPa. The 920 K-metallization process was carried out near the melting point of Al. This indicates that another type of reaction products is formed in this process.